Investment Risks - FT Vest Laddered Max Buffer ETF	Jun. 13, 2025
Absence Of An Active Market Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	ABSENCE OF AN ACTIVE MARKET RISK. The Fund faces numerous market trading risks, including the potential lack of an active market for Fund shares due to a limited number of market makers or authorized participants. The Fund may rely on a small number of third-party market makers to provide a market for the purchase and sale of shares and market makers are under no obligation to make a market in the Fund’s shares. Additionally, only a limited number of institutions act as authorized participants for the Fund and only an authorized participant may engage in creation or redemption transactions directly with the Fund and are not obligated to submit purchase or redemption orders for Creation Units. Decisions by market makers or authorized participants to reduce their role or step away from these activities in times of market stress could inhibit the effectiveness of the arbitrage process in maintaining the relationship between the underlying values of the Fund’s portfolio securities and the Fund’s market price. Any trading halt or other problem relating to the trading activity of these market makers or any issues disrupting the authorized participants’ ability to proceed with creation and/or redemption orders could result in a dramatic change in the spread between the Fund’s net asset value and the price at which the Fund’s shares are trading on the Exchange, which could result in a decrease in value of the Fund’s shares. This reduced effectiveness could result in Fund shares trading at a premium or discount to net asset value and also in greater than normal intraday bid-ask spreads for Fund shares.
Buffer Change Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	BUFFER CHANGE RISK. A new buffer for each Underlying ETF is established at the beginning of each Target Outcome Period and is dependent on prevailing market conditions. As a result, the buffer for an Underlying ETF may rise or fall from one Target Outcome Period to the next and is unlikely to remain the same for consecutive Target Outcome Periods. Each Underlying ETF aims to provide the maximum available buffer against SPY losses for each Target Outcome Period. The possible expected range of the buffer for a Target Outcome Period is between 20% and 100%, however, each Underlying ETF will alert shareholders, including the Fund, to a more precise expected buffer range for subsequent Target Outcome Periods approximately one week before the commencement of each Target Outcome Period, as described above. There is no guarantee that the final buffer set for a Target Outcome Period will be within the estimated range. The buffer may be established at the lower end or below the expected range, which would expose investors, like the Fund, with potential for greater losses than if higher buffers had been in effect.
Buffered Loss Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	BUFFERED LOSS RISK. There can be no guarantee that the Underlying ETFs will be successful in their strategy to buffer against SPY losses if SPY decreases over a Target Outcome Period by the buffered amount or less. The Fund may lose its entire investment in an Underlying ETF. Each Underlying ETF’s strategy seeks to deliver returns (before fees and expenses) that match the price return of SPY (up to the cap), while limiting downside losses, if shares are bought on the first day of a Target Outcome Period and held until the end of that Target Outcome Period. To the extent the Fund acquires shares of the Underlying ETFs in connection with creations of new shares of the Fund and during each quarterly rebalancing, the Fund typically will not acquire Underlying ETF shares on the first day of a Target Outcome Period. Likewise, to the extent the Fund disposes of shares of the Underlying ETFs in connection with redemptions of shares of the Fund and during each quarterly rebalancing, any such dispositions typically will not occur on the last day of a Target Outcome Period. In the event that the Fund acquires shares after the first day of a Target Outcome Period or disposes of shares prior to the end of a Target Outcome Period, the buffer that the Underlying ETF seeks to provide may not be available. If a buffer for a Target Outcome Period is less than 100%, and if the Fund purchases Underlying ETF shares during a Target Outcome Period at a time when the Underlying ETF has decreased in value by more than the buffered amount from the value of the Underlying ETF on the first day of the Target Outcome Period (the “Initial Underlying ETF Value”), the Fund’s buffer will essentially be zero (meaning the Fund can lose its entire investment). If the Fund purchases Underlying ETF shares at a time when the Underlying ETF has decreased in value by less than the buffered amount from the Initial Underlying ETF Value, the Fund’s buffer will be reduced by the difference between the Initial Underlying ETF Value and the NAV of the Underlying ETF on the date the Fund purchases the shares. An investor like the Fund that holds Underlying ETF shares through multiple Target Outcome Periods will be unable to recapture losses from prior Target Outcome Periods because at the end of each Target Outcome Period, a new buffer will be established based on the then current price of SPY and any losses experienced below the prior buffer will be locked in.
Cap Change Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	CAP CHANGE RISK. A new Underlying ETF cap is established at the beginning of each Target Outcome Period and is dependent on prevailing market conditions. As a result, a cap may rise or fall from one Target Outcome Period to the next and is unlikely to remain the same for consecutive Target Outcome Periods.
Capped Upside Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	CAPPED UPSIDE RISK. Each Underlying ETF’s strategy seeks to provide returns (before fees and expenses) that match the price return of SPY for shares acquired on the first day of a Target Outcome Period and held for the entire Target Outcome Period, subject to a pre-determined upside cap. Because the Fund will acquire shares of the Underlying ETFs in connection with creations of new shares of the Fund and during each quarterly rebalance, the Fund typically will not acquire Underlying ETF shares on the first day of a Target Outcome Period. Likewise, the Fund will dispose of shares of the Underlying ETFs in connection with redemptions of shares of the Fund and during each quarterly rebalance, and such disposals typically will not occur on the last day of a Target Outcome Period. In the event that the Fund acquires Underlying ETF shares after the first day of a Target Outcome Period and the Underlying ETF has risen in value to a level near to the cap, there may be little or no ability for the Fund to experience an investment gain on its shares (because the Fund’s potential gain will be limited to the difference between the Underlying ETF's NAV on the date the Fund purchases Underlying ETF shares and the cap), however, the Fund will remain vulnerable to downside risks. This could be true for all of the Underlying ETFs held by the Fund at a certain point in time severely limiting the Fund's ability to participate in gains during that time. If SPY experiences gains during a Target Outcome Period, an Underlying ETF will not participate in those gains beyond the cap. If the Fund buys Underlying ETF shares when the price exceeds the cap, the Fund will not experience any gain regardless of the performance of SPY. An investor like the Fund that holds Underlying ETF shares through multiple Target Outcome Periods may fail to experience gains comparable to those of SPY over time because at the end of each Target Outcome Period, a new cap will be established based on the then current price of SPY and any gains above the prior cap will be forfeit. Moreover, the annual imposition of a new cap on future gains may make it difficult to recoup any losses from prior Target Outcome Periods such that, over multiple Target Outcome Periods, the Underlying ETFs may have losses that exceed those of SPY.
Counterparty Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	COUNTERPARTY RISK. Underlying ETF transactions involving a counterparty are subject to the risk that the counterparty will not fulfill its obligation to the Underlying ETF. Counterparty risk may arise because of the counterparty’s financial condition (i.e., financial difficulties, bankruptcy, or insolvency), market activities and developments, or other reasons, whether foreseen or not. A counterparty’s inability to fulfill its obligation may result in significant financial loss to the Fund. An Underlying ETF may be unable to recover its investment from the counterparty or may obtain a limited recovery, and/or recovery may be delayed. The OCC acts as guarantor and central counterparty with respect to the FLEX Options. As a result, the ability of an Underlying ETF to meet its objective depends on the OCC being able to meet its obligations. In the unlikely event that the OCC becomes insolvent or is otherwise unable to meet its settlement obligations, an Underlying ETF and, in turn, the Fund could suffer significant losses.
Current Market Conditions Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	CURRENT MARKET CONDITIONS RISK. Current market conditions risk is the risk that a particular investment, or shares of the Fund in general, may fall in value due to current market conditions. As a means to fight inflation, which remains at elevated levels, the Federal Reserve and certain foreign central banks have raised interest rates; however, the Federal Reserve has recently lowered interest rates and may continue to do so. U.S. regulators have proposed several changes to market and issuer regulations which would directly impact the Fund, and any regulatory changes could adversely impact the Fund’s ability to achieve its investment strategies or make certain investments. Recent and potential future bank failures could result in disruption to the broader banking industry or markets generally and reduce confidence in financial institutions and the economy as a whole, which may also heighten market volatility and reduce liquidity. Additionally, challenges in commercial real estate markets, including rising interest rates, declining valuations and increasing vacancies, could have a broader impact on financial markets. The ongoing adversarial political climate in the United States, as well as political and diplomatic events both domestic and abroad, have and may continue to have an adverse impact the U.S. regulatory landscape, markets and investor behavior, which could have a negative impact on the Fund’s investments and operations. The change in administration resulting from the 2024 United States national elections could result in significant impacts to international trade relations, tax and immigration policies, and other aspects of the national and international political and financial landscape, which could affect, among other things, inflation and the securities markets generally. Other unexpected political, regulatory and diplomatic events within the U.S. and abroad may affect investor and consumer confidence and may adversely impact financial markets and the broader economy. For example, ongoing armed conflicts between Russia and Ukraine in Europe and among Israel, Iran, Hamas and other militant groups in the Middle East, have caused and could continue to cause significant market disruptions and volatility within the markets in Russia, Europe, the Middle East and the United States. The hostilities and sanctions resulting from those hostilities have and could continue to have a significant impact on certain Fund investments as well as Fund performance and liquidity. The economies of the United States and its trading partners, as well as the financial markets generally, may be adversely impacted by trade disputes, including the imposition of tariffs, and other matters. For example, the United States has imposed trade barriers and restrictions on China. In addition, the Chinese government is engaged in a longstanding dispute with Taiwan, continually threatening an invasion. If the political climate between the United States and China does not improve or continues to deteriorate, if China were to attempt invading Taiwan, or if other geopolitical conflicts develop or worsen, economies, markets and individual securities may be adversely affected, and the value of the Fund’s assets may go down. A public health crisis and the ensuing policies enacted by governments and central banks may cause significant volatility and uncertainty in global financial markets, negatively impacting global growth prospects. As the COVID-19 global pandemic illustrated, such events may affect certain geographic regions, countries, sectors and industries more significantly than others. Advancements in technology may also adversely impact markets and the overall performance of the Fund. For instance, the economy may be significantly impacted by the advanced development and increased regulation of artificial intelligence. Additionally, cyber security breaches of both government and non-government entities could have negative impacts on infrastructure and the ability of such entities, including the Fund, to operate properly. These events, and any other future events, may adversely affect the prices and liquidity of the Fund’s portfolio investments and could result in disruptions in the trading markets.
Cyber Security Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	CYBER SECURITY RISK. The Fund is susceptible to operational risks through breaches in cyber security. A breach in cyber security refers to both intentional and unintentional events that may cause the Fund to lose proprietary information, suffer data corruption or lose operational capacity. Such events could cause the Fund to incur regulatory penalties, reputational damage, additional compliance costs associated with corrective measures and/or financial loss. Cyber security breaches may involve unauthorized access to the Fund’s digital information systems through “hacking” or malicious software coding but may also result from outside attacks such as denial-of-service attacks through efforts to make network services unavailable to intended users. In addition, cyber security breaches of the issuers of securities in which the Fund invests or the Fund’s third-party service providers, such as its administrator, transfer agent, custodian, or sub-advisor, as applicable, can also subject the Fund to many of the same risks associated with direct cyber security breaches. Although the Fund has established risk management systems designed to reduce the risks associated with cyber security, there is no guarantee that such efforts will succeed, especially because the Fund does not directly control the cyber security systems of issuers or third-party service providers.
Flex Options Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	FLEX OPTIONS RISK. The Underlying ETFs invest in FLEX Options. Trading FLEX Options involves risks different from, or possibly greater than, the risks associated with investing directly in securities. The Underlying ETFs may experience substantial downside from specific FLEX Option positions and certain FLEX Option positions may expire worthless. The FLEX Options are listed on an exchange; however, no one can guarantee that a liquid secondary trading market will exist for the FLEX Options. In the event that trading in the FLEX Options is limited or absent, the value of the Underlying ETFs' FLEX Options may decrease. In a less liquid market for the FLEX Options, liquidating the FLEX Options may require the payment of a premium (for written FLEX Options) or acceptance of a discounted price (for purchased FLEX Options) and may take longer to complete. A less liquid trading market may adversely impact the value of the FLEX Options and Underlying ETFs’ shares and result in the Underlying ETFs and, in turn, the Fund being unable to achieve their investment objective. Less liquidity in the trading of the Underlying ETF's FLEX Options could have an impact on the prices paid or received by the Underlying ETFs for the FLEX Options in connection with creations and redemptions of the Underlying ETF’s shares. Depending on the nature of this impact to pricing, an Underlying ETF may be forced to pay more for redemptions (or receive less for creations) than the price at which it currently values the FLEX Options. Such overpayment or under collection may impact the value of the Underlying ETF and whether the Underlying ETF can satisfy its investment objective. Additionally, in a less liquid market for the FLEX Options, the liquidation of a large number of options may more significantly impact the price. A less liquid trading market may adversely impact the value of the FLEX Options and the value of the Underlying ETFs. The trading in FLEX Options may be less deep and liquid than the market for certain other exchange-traded options, non-customized options or other securities.
Flex Options Valuation Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	FLEX OPTIONS VALUATION RISK. The FLEX Options held by the Underlying ETFs will be exercisable at the strike price only on their expiration date. Prior to the expiration date, the value of the FLEX Options will be determined based upon market quotations or using other recognized pricing methods. The FLEX Options are also subject to correlation risk, meaning the value of the FLEX Options does not increase or decrease at the same rate as SPY (although they generally move in the same direction) or its underlying securities. The value of the FLEX Options prior to the expiration date may vary because of factors other than the value of SPY, such as interest rate changes, changing supply and demand, decreased liquidity of the FLEX Options, a change in the actual and perceived volatility of the stock market and SPY and the remaining time to expiration. FLEX Option prices may also be highly volatile and may fluctuate substantially during a short period of time. During periods of reduced market liquidity or in the absence of readily available market quotations for the holdings of the Underlying ETFs, the ability of the Underlying ETFs to value the FLEX Options becomes more difficult and the judgment of the Underlying ETFs' investment adviser (employing the fair value procedures approved by the Board of Trustees of the Trust) may play a greater role in the valuation of the Underlying ETFs' holdings due to reduced availability of reliable objective pricing data. Consequently, while such determinations may be made in good faith, it may nevertheless be more difficult for the Underlying ETFs to accurately assign a daily value. Under those circumstances, the value of the FLEX Options will require more reliance on the investment adviser’s judgment than that required for securities for which there is an active trading market. This creates a risk of mispricing or improper valuation of the FLEX Options which could impact the value paid for shares of the Underlying ETFs.
Index Or Model Constituent Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	INDEX OR MODEL CONSTITUENT RISK. The Fund may be a constituent of one or more indices or ETF models. As a result, the Fund may be included in one or more index-tracking exchange-traded funds or mutual funds. Being a component security of such a vehicle could greatly affect the trading activity involving the Fund’s shares, the size of the Fund and the market volatility of the Fund. Inclusion in an index could increase demand for the Fund and removal from an index could result in outsized selling activity in a relatively short period of time. As a result, the Fund’s net asset value could be negatively impacted and the Fund’s market price may be below the Fund’s net asset value during certain periods. In addition, index rebalances may potentially result in increased trading activity in the Fund's shares.
Information Technology Companies Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	INFORMATION TECHNOLOGY COMPANIES RISK. SPY invests significantly in information technology companies. Information technology companies produce and provide hardware, software and information technology systems and services. These companies may be adversely affected by rapidly changing technologies, short product life cycles, fierce competition, aggressive pricing and reduced profit margins, the loss of patent, copyright and trademark protections, cyclical market patterns, evolving industry standards and frequent new product introductions. In addition, information technology companies are particularly vulnerable to federal, state and local government regulation, and competition and consolidation, both domestically and internationally, including competition from foreign competitors with lower production costs. Information technology companies also heavily rely on intellectual property rights and may be adversely affected by the loss or impairment of those rights.
Large Capitalization Companies Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	LARGE CAPITALIZATION COMPANIES RISK. SPY invests in the securities of large capitalization companies. Large capitalization companies may grow at a slower rate and be less able to adapt to changing market conditions than smaller capitalization companies. Thus, the return on investment in securities of large capitalization companies may be less than the return on investment in securities of small and/or mid capitalization companies. The performance of large capitalization companies also tends to trail the overall market during different market cycles.
Management Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	MANAGEMENT RISK. The Fund is subject to management risk because it is an actively managed portfolio. In managing the Fund’s investment portfolio, the portfolio managers will apply investment techniques and risk analyses, including through the use of technology, automated processes, algorithms, or other management systems, that may not operate as intended or produce the desired result. There can be no guarantee that the Fund will meet its investment objective.
Market Fluctuation Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	MARKET FLUCTUATION TAX RISK. The Fund is acquiring shares of the Underlying ETFs in the open market. When the Fund sells shares of the Underlying ETFs in the open market, the Fund will recognize gain or loss on the disposition of the shares, which could have a negative impact on Fund returns. In addition, note that the Fund may, under certain circumstances, effect a portion of its creations and redemptions for cash rather than in-kind. If the Fund effects redemptions for cash, it may be required to sell shares of the Underlying ETFs in order to obtain the cash needed to distribute redemption proceeds. Any recognized gain on these sales by the Fund will generally cause the Fund to recognize a gain it might not otherwise have recognized, or to recognize such gain sooner than would otherwise be required if it were to distribute such shares only in-kind. The Fund intends to distribute these gains to shareholders to avoid being taxed on this gain at the fund level and otherwise comply with the special tax rules that apply to it. This strategy may cause shareholders to be subject to tax on gains they would not otherwise be subject to, or at an earlier date than if they had made an investment in a different ETF. Moreover, cash transactions may have to be carried out over several days if the securities market is relatively illiquid and may involve considerable brokerage fees and taxes. These brokerage fees and taxes, which will be higher than if the Fund sold and redeemed its shares entirely in-kind, will be passed on to those purchasing and redeeming Creation Units in the form of creation and redemption transaction fees. In addition, these factors may result in wider spreads between the bid and the offered prices of the Fund’s shares than for ETFs that distribute portfolio securities in-kind. The Fund’s use of cash for creations and redemptions could also result in dilution to the Fund and increased transaction costs, which could negatively impact the Fund’s ability to achieve its investment objective.
Market Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	MARKET RISK. Market risk is the risk that a particular investment, or shares of the Fund in general, may fall in value. Securities are subject to market fluctuations caused by real or perceived adverse economic, political, and regulatory factors or market developments, changes in interest rates and perceived trends in securities prices. Shares of the Fund could decline in value or underperform other investments. In addition, local, regional or global events such as war, acts of terrorism, market manipulation, government defaults, government shutdowns, regulatory actions, political changes, diplomatic developments, the imposition of sanctions and other similar measures, spread of infectious diseases or other public health issues, recessions, natural disasters, or other events could have a significant negative impact on the Fund and its investments. Any of such circumstances could have a materially negative impact on the value of the Fund’s shares, the liquidity of an investment, and may result in increased market volatility. During any such events, the Fund’s shares may trade at increased premiums or discounts to their net asset value, the bid/ask spread on the Fund’s shares may widen and the returns on investment may fluctuate.
New Fund Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	NEW FUND RISK. The Fund is new and has no performance history or assets as of the date of this prospectus. The Fund expects to have fewer assets than larger funds. Like other new funds, large inflows and outflows may impact the Fund’s market exposure, and in turn, the Fund’s returns for limited periods of time.
Risk Nondiversified [Member]
Prospectus [Line Items]
Risk [Text Block]	NON-DIVERSIFICATION RISK. The Fund is classified as “non-diversified” under the 1940 Act. As a result, the Fund is only limited as to the percentage of its assets which may be invested in the securities of any one issuer by the diversification requirements imposed by the Internal Revenue Code of 1986, as amended (the "Code"). The Fund may invest a relatively high percentage of its assets in a limited number of issuers. As a result, the Fund may be more susceptible to a single adverse economic or regulatory occurrence affecting one or more of these issuers, experience increased volatility and be highly invested in certain issuers.
Operational Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	OPERATIONAL RISK. The Fund is subject to risks arising from various operational factors, including, but not limited to, human error, processing and communication errors, errors of the Fund’s service providers, counterparties or other third-parties, failed or inadequate processes and technology or systems failures. The Fund relies on third-parties for a range of services, including custody. Any delay or failure relating to engaging or maintaining such service providers may affect the Fund’s ability to meet its investment objective. Although the Fund and the Fund's investment advisor seek to reduce these operational risks through controls and procedures, there is no way to completely protect against such risks.
Options Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	OPTIONS RISK. The use of options involves investment strategies and risks different from those associated with ordinary portfolio securities transactions and depends on the ability of the Underlying ETFs' portfolio managers to forecast market movements correctly. The prices of options are volatile and are influenced by, among other things, actual and anticipated changes in the value of the underlying instrument, or in interest or currency exchange rates, including the anticipated volatility, which in turn are affected by fiscal and monetary policies and by national and international political and economic events. The effective use of options also depends on the Underlying ETFs' ability to terminate option positions at times deemed desirable to do so. There is no assurance that the Underlying ETFs will be able to effect closing transactions at any particular time or at an acceptable price. In addition, there may at times be an imperfect correlation between the movement in values of options and their underlying securities and there may at times not be a liquid secondary market for certain options.
Portfolio Turnover Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	PORTFOLIO TURNOVER RISK. High portfolio turnover may result in the Fund paying higher levels of transaction costs and may generate greater tax liabilities for shareholders. Portfolio turnover risk may cause the Fund’s performance to be less than expected.
Premium Discount Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	PREMIUM/DISCOUNT RISK. The market price of the Fund’s shares will generally fluctuate in accordance with changes in the Fund’s net asset value as well as the relative supply of and demand for shares on the Exchange. The Fund’s investment advisor cannot predict whether shares will trade below, at or above their net asset value because the shares trade on the Exchange at market prices and not at net asset value. Price differences may be due, in large part, to the fact that supply and demand forces at work in the secondary trading market for shares will be closely related, but not identical, to the same forces influencing the prices of the holdings of the Fund trading individually or in the aggregate at any point in time. However, given that shares can only be purchased and redeemed in Creation Units, and only to and from broker-dealers and large institutional investors that have entered into participation agreements (unlike shares of closed-end funds, which frequently trade at appreciable discounts from, and sometimes at premiums to, their net asset value), the Fund’s investment advisor believes that large discounts or premiums to the net asset value of shares should not be sustained. During stressed market conditions, the market for the Fund’s shares may become less liquid in response to deteriorating liquidity in the market for the Fund’s underlying portfolio holdings, which could in turn lead to differences between the market price of the Fund’s shares and their net asset value and the bid/ask spread on the Fund’s shares may widen.
Significant Exposure Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	SIGNIFICANT EXPOSURE RISK. The Fund intends to generally rebalance its portfolio to equal weight quarterly. In between such rebalances, market movements in the prices of the Underlying ETFs may result in the Fund having temporary larger exposures to certain Underlying ETFs compared to others. Under such circumstances, the Fund’s returns would be more greatly influenced by the returns of the Underlying ETFs with the larger exposures.
Spy Equity Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	SPY EQUITY RISK. Because each Underlying ETF holds FLEX Options that reference SPY, each Underlying ETF has exposure to the equity securities markets. Equity securities prices fluctuate for several reasons, including changes in investors’ perceptions of the financial condition of an issuer or the general condition of the relevant equity market, such as market volatility, or when political or economic events affecting an issuer occur. Common stock prices may be particularly sensitive to rising interest rates, as the cost of capital rises and borrowing costs increase. Equity securities may decline significantly in price over short or extended periods of time, and such declines may occur in the equity market as a whole, or they may occur in only a particular country, company, industry or sector of the market.
Spy Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	SPY RISK. Each Underlying ETF invests in FLEX Options that reference SPY, which subjects the Underlying ETFs to certain of the risks of owning shares of an ETF as well as the types of instruments in which SPY invests. The value of SPY will fluctuate over time based on fluctuations in the values of the securities held by SPY, which may be affected by changes in general economic conditions, expectations for future growth and profits, interest rates and the supply and demand for those securities. In addition, ETFs are subject to absence of an active market risk, premium/discount risk and trading issues risk. Brokerage, tax and other expenses may negatively impact the performance of the Underlying ETF and, in turn, the value of the Fund’s shares. An ETF that tracks an index may not exactly match the performance of the index due to cash drag, differences between the portfolio of the ETF and the components of the index, expenses and other factors.
Target Outcome Period Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	TARGET OUTCOME PERIOD RISK. Each Underlying ETF’s investment strategy is designed to deliver returns that match the price return of SPY if shares are bought on the day on which the Underlying ETF enters into the FLEX Options (i.e., the first day of a Target Outcome Period) and held until those FLEX Options expire at the end of the Target Outcome Period subject to the cap.Because the Fund will acquire shares of the Underlying ETFs in connection with creations of new shares of the Fund and during each quarterly rebalance, the Fund typically will not acquire Underlying ETF shares on the first day of a Target Outcome Period. Likewise, the Fund will dispose of shares of the Underlying ETFs in connection with redemptions of shares of the Fund and during each quarterly rebalance, and such disposals typically will not occur on the last day of a Target Outcome Period. In the event the Fund acquires shares after the first day of a Target Outcome Period or disposes of shares prior to the expiration of the Target Outcome Period, the value of the Fund’s investment in Underlying ETF shares may not be buffered against a decline in the value of SPY and may not participate in a gain in the value of SPY for the Fund’s investment period.
Tax Risk From Investment In Other Investment Companies [Member]
Prospectus [Line Items]
Risk [Text Block]	TAX RISK FROM INVESTMENT IN OTHER INVESTMENT COMPANIES. The Fund has based its analysis of its qualification as a “regulated investment company” (“RIC”) as defined by the Code on the belief that its portfolio funds are themselves RICs. If a portfolio fund were to lose its status as a RIC for purposes of the Code, the Fund may fail its requirement to have a diversified portfolio, and, thus, lose its own RIC status. If the Fund did not qualify as a RIC for any taxable year and certain relief provisions were not available, the Fund’s taxable income would be subject to tax at the Fund level and to a further tax at the shareholder level when such income is distributed. In such event, in order to re-qualify for taxation as a RIC, the Fund might be required to recognize unrealized gains, pay substantial taxes and interest and make certain distributions. This would cause investors to incur higher tax liabilities than they otherwise would have incurred and would have a negative impact on Fund returns. In such event, the Fund’s Board of Trustees may determine to reorganize or close the Fund or materially change the Fund’s investment objective and strategies. In the event that the Fund fails to qualify as a RIC, the Fund will promptly notify shareholders of the implications of that failure.
Trading Issues Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	TRADING ISSUES RISK. Trading in Fund shares on the Exchange may be halted due to market conditions or for reasons that, in the view of the Exchange, make trading in shares inadvisable. In addition, trading in Fund shares on the Exchange is subject to trading halts caused by extraordinary market volatility pursuant to the Exchange’s “circuit breaker” rules. There can be no assurance that the requirements of the Exchange necessary to maintain the listing of the Fund will continue to be met or will remain unchanged. The Fund may have difficulty maintaining its listing on the Exchange in the event the Fund’s assets are small, the Fund does not have enough shareholders, or if the Fund is unable to proceed with creation and/or redemption orders.
Underlying ETF Concentration Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	UNDERLYING ETF CONCENTRATION RISK. An Underlying ETF may be susceptible to an increased risk of loss, including losses due to adverse events that affect the Underlying ETF's investments more than the market as a whole, to the extent that the Underlying ETF's investments are concentrated in the securities and/or other assets of a particular issuer or issuers, country, group of countries, region, market, industry, group of industries, sector, market segment or asset class.
Underlying ETF Exposure Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	UNDERLYING ETF EXPOSURE RISK. An investment in the Fund may provide returns that are lower than the returns that an investor could achieve by investing in one or more of the Underlying ETFs alone. Additionally, if one or more of the Underlying ETFs has exceeded its cap at the time that you invest in the Fund, you may derive no benefit from the Fund’s investment in that Underlying ETF until the next reset of the Underlying ETF. Likewise, if one or more of the Underlying ETFs has decreased in value below its buffer at the time that you invest in the Fund, you may derive no buffered protection from the Fund’s investment in that Underlying ETF. See Buffered Loss Risk and Capped Upside Risk above. As a shareholder in other ETFs, the Fund bears its proportionate share of each ETF’s expenses, subjecting Fund shareholders to duplicative expenses. The Fund does not itself pursue a target outcome strategy and does not provide any buffer against Underlying ETF losses.
Underlying ETF Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	UNDERLYING ETF RISK. The Fund’s investment in shares of the Underlying ETFs subjects it to the risks of owning the securities held by the Underlying the ETF, as well as the same structural risks faced by an investor purchasing shares of the Fund, including absence of an active market risk, premium/discount risk and trading issues risk. As a shareholder in another ETF, the Fund bears its proportionate share of the ETF’s expenses, subjecting Fund shareholders to duplicative expenses.
Risk Lose Money [Member]
Prospectus [Line Items]
Risk [Text Block]	You could lose money by investing in the Fund.
Risk Not Insured Depository Institution [Member]
Prospectus [Line Items]
Risk [Text Block]	An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.